The present invention relates to a method for regulating clearance for a vehicle, in which a relative speed and a relative distance between the vehicle and a second vehicle driving ahead of it are detected, and a control signal for an adaptive cruise control device of the vehicle is generated from these quantities; and also relates to a device for implementing the method.
German laid open application 42 00 694 A1 describes a method for regulating speed and distance of a vehicle with respect to an object located ahead of it in the direction of to travel. In that known method, the prevailing distance, as well as the instantaneous speed of the vehicle, are detected, and setpoint values for the distance to the object located in front of the vehicle and for the driving speed are calculated and set. A problem with this method, and with other known methods that enable a vehicle to be driven while regulating clearance, is that adaptive cruise controls are conceived as driver-supporting systems whose acceptance by the driver depends on how similar the control response is to his/her own driving behavior, especially in maintaining the distance to a vehicle driving ahead.
The publication xe2x80x9cAbstandsregelung von Fahrzeugen mit Fuzzy-Controlxe2x80x9d [xe2x80x9cRegulating the Spacing of Vehicles Using Fuzzy Controlxe2x80x9d], symposium volume of minutes of the Third Dortmunder Fuzzy Days Symposium, Reihe Informatik Aktuell [Current Series on Information Studies], Springer Publishers 1993 suggests determining a distance model which is a function of the type of driver and the weather instead of a definite specified setpoint distance. According to this proposal, the type of driver would be determined by an external sensory mechanism; however, a method for reliably recognizing the type of driver automatically is not described in the aforementioned publication.
Applicant""s earlier patent application EP 0 813 986 A2 discloses a method for regulating clearance for a vehicle, in which the setpoint distance to a second vehicle driving ahead is determined. This method employs a device for calculating the setpoint distance as a function of at least the driving speed of the vehicle. The response characteristics of the device may be adapted to the individual driving behavior of a vehicle driver, in the sense that the individual time interval between the vehicle and the second vehicle ahead is maintained by determining the setpoint distance. The device includes a fuzzy controller that receives driving speed as input variable and at least one additional input variable, and a setpoint distance is generated as the output variable. In addition, control equipment is provided in which truth values for the setpoint distance are determined from truth values for the input variables, and an output matching function is provided with which the setpoint distance to be reset is determined from the truth values of the setpoint distance. To carry out this control, a number of classes are established over the range of values of the input variables, and value combinations of the input variables and the distance values occurring in a learning phase are recorded. The established classes are modified, discarded, and/or new classes are generated as a function of the recorded value combinations, and adapted control equipment rules are generated as a function of the matching functions adapted to the established classes.
It may be that such a method allows the adaptive cruise control to be acceptably adjusted to a vehicle driver and, therefore, increases the acceptance of such a method.
However, it has the disadvantage that the fuzzy logic to be used in this case is relatively complex and, therefore, the device is expensive and costly to manufacture.
It is an object of the present invention to provide a method and a device for regulating distance of a vehicle and a second vehicle ahead of it, in such a way that, given a simple design, the control response of the method according to the present invention can be adjusted to the driving behavior of an individual vehicle driver.
It is another object of the invention to provide a method and device, adapted to an individual vehicle driver, for regulating the distance between a vehicle and a second vehicle ahead of it which are characterized by their acceptance-promoting control response and ability to be easily implemented. Advantageously, the device for carrying out the method according to the present invention is relatively simple and low cost. In addition, complicated, and thus, time- and device-intensive learning processes are no longer necessary so that the method of the present invention is especially applicable to regulating clearance during cutting-in maneuvers, in which an overtaking vehicle passes the vehicle equipped with the adaptive cruise control method of the present invention and enters back into the lane in front of it.
The foregoing objectives are achieved according to the present invention by determining a danger criterion based on the relative speed and the relative distance between two moving vehicles, by weighting this danger criterion with an adaptive factor representing the individual driving behavior of the vehicle driver, and by generating a control signal causing the vehicle to decelerate when the danger criterion, which is weighted with the adaptive factor and adjusted to the vehicle driver, exceeds a defined threshold value.
The present invention provides a method for regulating clearance for a vehicle, in which a relative velocity (vrel) and a relative distance (a) between the vehicle and a vehicle driving ahead is detected, and a control signal (RV) for an adaptive cruise control device of the vehicle is generated from these quantities, wherein a danger criterion (G) is determined from the relative velocity (vrel) and the relative distance (a); that this danger criterion (G) is weighted with an adaptive factor (AF) representing the individual driving behavior of the driver of the vehicle; and that a control signal (RV) initiating deceleration of the vehicle is generated when the danger criterion (GF) weighted with the adaptive factor (AF) and adjusted to the vehicle driver, falls below a defined threshold value (S).
The present invention also provides a device for regulating clearance that operates in accordance with the above-described method.
Further details and advantages of the present invention can be taken from the exemplary embodiment, which is described below with reference to the Figures.